The invention relates to a video endoscope, comprising an elongate shaft having a longitudinal axis, and a handpiece at the proximal end of the shaft, a distal end of the shaft being provided with a lens and, in the proximal direction from the lens, with an electronic image pickup, the image pickup being connected, via an electrical connection extending along the shaft, to an electrical connector piece arranged in the area of the handpiece, and the image pickup and the connector piece being able to rotate relative to each other about the longitudinal axis of the shaft.
A video endoscope is a viewing instrument used in medical endoscopy. Use of a video endoscope in the field of minimally invasive surgery allows regions of the body to be reached by way of natural openings in the body and also by way of artificial incisions that have been created surgically. In endoscopes in general, a distinction is made between those with a rigid elongate shaft and those with a flexible elongate shaft. The present invention can be applied to both rigid video endoscopes and flexible video endoscopes.
A video endoscope is a special type of endoscope in which the images are picked up and conveyed not by a lens system or an organized bundle of optical fibres, but instead by an electronic image pickup and electrical leads.
Since miniaturized electronic image pickups are presently available, for example in CCD or CMOS technology, it is possible to arrange the electronic image pickup in the distal end of the shaft. The object being viewed is projected onto the image pickup via a lens arranged in the distal direction from the electronic image pickup. The electronic image pickup converts the received photons into electrical signals, which are carried in the proximal direction to an electrical connector piece by way of one or more electrical leads that extend from the image pickup all the way through the shaft to the handpiece of the video endoscope. By way of the electrical connector piece, the video endoscope is connected by means of a cable to an image-processing unit that includes a monitor, and the image recorded by the image pickup is displayed on the monitor. The electrical connection extending through the shaft is also used to control and supply power to the distal image pickup.
In video endoscopes with a distal electronic image pickup, the orientation of the physician relative to the video image displayed on the screen is made difficult if the video endoscope is rotated about its longitudinal axis during viewing of a region of the body. If the image pickup is fixed in terms of rotation relative to the shaft, the image pickup is also rotated about its longitudinal axis along with the rotation of the video endoscope, which necessarily causes rotation of the image on the monitor.
In video endoscopes in which the lens has a straight view optic or so-called 0° optic, this problem of orientation can be overcome by means of markings on the handgrip and in the monitor image.
However, this problem is more serious in video endoscopes in which the lens has an oblique optic, for example a 30°, 45° or 90° optic. When a video endoscope with an oblique optic is rotated about its longitudinal axis, the viewing direction changes, as also does the orientation of the viewed image, with respect to top, bottom, right and left. Even with markings on the handgrip of the video endoscope and in the monitor image, the physician is unable to reliably orient himself spatially in the observed region of the body.
For this reason, concepts were proposed in which the image on the monitor can be corrected in orientation, such that the image on the monitor at all times has a defined orientation with respect to top, bottom, right and left.
One of these concepts involves rotating the monitor itself. Although rotation of the monitor is possible, it requires complex electromechanical attachments, which in the operating environment are to be seen as critical. In addition, the usual 4:3 or 16:9 (HDTV) image size is not especially suitable for a mechanical or even an analogue electronic rotation, as is described in EP 712 289 A1.
Another concept is for the image shown on the monitor to be rotated by means of image processing, such as is described in U.S. Pat. No. 5,313,306, for example. However, image correction by means of digital image processing has the disadvantage that no full-format 4:3 image can be rotated without loss of information. Only the inscribed circle in the 3:3 square can be rotated without loss of information. However, the physicians working with video endoscopes are familiar with full-format images, especially in laparoscopy (surgery of the abdominal cavity), and with corresponding full-format image information and do not want to do without these.
The third concept of image correction, from which the present invention starts out, involves making the electronic image pickup rotatable. When the video endoscope is rotated about its longitudinal axis, the image pickup, in order to maintain a defined orientation, can be kept spatially fixed by rotation relative to the shaft and relative to the lens fixed to the shaft. The image pickup is thereby not coupled to the lens, which is of advantage especially in the case of an oblique view lens.
However, the rotatability of the image pickup relative to the shaft and thus also to the proximal electrical connector piece imposes other demands on the video endoscope, particularly on the electrical connection between the image pickup and the proximal electrical connector piece.
Upon rotation of the image pickup relative to the shaft, the at least one electrical connection between the image pickup and the electrical connector piece is necessarily rotated if the electrical connector piece at the proximal end of the handpiece is fixed in terms of rotation with respect to the shaft.
In the document DE 201 13 031 U1, the electrical connection between the image pickup and the electrical connector piece is formed by a multicore cable. Since the rotatability of the image pickup in a video endoscope with an oblique view optic should be possible both clockwise and anticlockwise through 180°, the multicore cable is correspondingly subjected to considerable torsion. After a certain number of changes of load and/or after several sterilizations in an autoclave, the cable has a tendency to break, which has the disadvantage of shortening the useful life of the video endoscope.
To solve this problem, DE 201 13 031 U1 proposes that a sliding contact be provided at the proximal end of the cable, such that the cable, together with the image pickup, can be rotated in a manner free of torsion about its longitudinal axis relative to the electrical connector piece. However, this solution has the disadvantage that it is structurally very complicated and is also susceptible to malfunction.
Another disadvantage of designing the electrical connection as a multicore cable is the great complexity of producing the video endoscope, because each core has to be individually connected to the image pickup, which is very difficult, particularly in a miniaturized configuration of the image pickup.
U.S. Pat. No. 6,488,631 B2 discloses an ultrasound endoscope in which the electrical connection between distally arranged ultrasound transducers and proximal connector piece is formed, in the area of a distal bend of the endoscope, by a multiplicity of flexible circuit boards, which are cut from a tube. The electronic image pickup of this endoscope, by contrast, is electrically connected to the proximal connector piece by means of a multicore cable.